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US 9,319,596 B2Granted
Light-emitting device and camera
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsYoshiharu Hirakata, Nobuharu Ohsawa, Hisao Ikeda, Kazuhiko Fujita, Akihiro Kaita
Life of this patent
Estimating the term…
Abstract
A small light-emitting device is provided. A light-emitting device which is less likely to produce a shadow is provided. A structure including a switching circuit for supplying a pulsed constant current and a light-emitting panel supplied with the pulsed constant current has been conceived.
Claims13
A light-emitting device comprising:
- a battery for supplying a first voltage;
- a first DC-DC converter configured to be supplied with the first voltage and configured to supply a second voltage higher than the first voltage;
- a capacitor configured to be supplied with the second voltage;
- a second DC-DC converter configured to be supplied with power from the capacitor and configured to supply a constant current;
- a switching circuit configured to be supplied with the constant current and a control pulse signal and configured to supply a constant current pulse;
- a constant current power source configured to supply the constant current;
- a driver circuit configured to supply the control pulse signal, the driver circuit comprising a start switch;
- and
- a light-emitting panel configured to be supplied with the constant current pulse,
- wherein the driver circuit outputs the control pulse signal in response to a switching operation of the start switch so that the switching circuit supplies a constant current with a half width of more than or equal to 1 millisecond and less than or equal to 1000 milliseconds.
7 more elements
A light-emitting device comprising:
- a switching circuit configured to be supplied with a constant current and a control pulse signal and configured to supply a constant current pulse;
- a constant current power source configured to supply the constant current;
- a driver circuit configured to supply the control pulse signal, the driver circuit comprising a start switch;
- a counter circuit configured to count the number of times the driver circuit supplies the control pulse signal;
- and
- a light-emitting panel configured to be supplied with the constant current pulse,
- wherein the driver circuit outputs the control pulse signal in response to a switching operation of the start switch so that the switching circuit supplies a constant current with a half width of more than or equal to 1 millisecond and less than or equal to 1000 milliseconds.
4 more elements
A light-emitting device comprising:
- a battery for supplying a first voltage;
- a first DC-DC converter configured to be supplied with the first voltage and configured to supply a second voltage higher than the first voltage;
- a capacitor configured to be supplied with the second voltage;
- a second DC-DC converter configured to be supplied with power from the capacitor and configured to supply a constant current;
- a switching circuit configured to be supplied with the constant current and a control pulse signal and configured to supply a constant current pulse;
- a constant current power source configured to supply the constant current;
- a driver circuit configured to supply the control pulse signal, the driver circuit comprising a start switch;
- a counter circuit configured to count the number of times the driver circuit supplies the control pulse signal;
- and
- a light-emitting panel configured to be supplied with the constant current pulse,
- wherein the driver circuit outputs the control pulse signal in response to a switching operation of the start switch so that the switching circuit supplies a constant current with a half width of more than or equal to 1 millisecond and less than or equal to 1000 milliseconds.
8 more elements
Dependencies are inferred from the claim text.